The present invention relates generally to a new and novel all-wheel-drive motor vehicle transfer case with bevel gear differential. More particularly, the present invention relates to a new and novel all-wheel-drive motor vehicle transfer case with bevel gear differential which drives the front and rear axles of a motor vehicle and utilizes an interaxle differential housing having one-piece construction.
Four-wheel drive motor vehicles are becoming increasingly popular. Recently, certain motor vehicles have been provided with xe2x80x9cfull-timexe2x80x9d four-wheel drive systems capable of operation on hard pavement at highway speeds. In such xe2x80x9cfull-timexe2x80x9d four-wheel drive systems, the torque transfer cases are typically provided with an interaxle differential for dividing torque between the front wheels and the rear wheels of the motor vehicle. The interaxle differential enables the front wheels and the rear wheels to rotate at different speeds, which occurs during normal turning of the motor vehicle.
Known prior xe2x80x9cfull-timexe2x80x9d four-wheel drive systems have generally utilized planetary type gear designs. While such known prior art planetary type gear designs have generally performed well in motor vehicle transfer cases, they are, in many cases, more complex, and thus more expensive to fabricate, than a bevel type gear design. Accordingly, such known prior art motor vehicle transfer cases utilizing traditional planetary type gear designs are more complex, and thus more costly, than desired.
A preferred embodiment of the present invention is, therefore, directed to an all-wheel-drive motor vehicle transfer case with bevel gear differential including an interaxle differential and shafts for driving the front and rear axles of a motor vehicle. The interaxle differential includes a bevel gear design and utilizes an interaxle differential housing having one-piece construction and a transfer case housing having one-piece construction. A splined input shaft extending from the motor vehicle transmission mates with the inside diameter of a splined trunnion on the interaxle differential housing to provide input torque. A left side gear is splined to a rear output shaft and an expanding ring is utilized to minimize endplay of the rear output shaft. A right side gear is splined to an intermediate shaft which drives a chain sprocket and chain which, in turn, drives a front output shaft. The intermediate shaft includes a shoulder and a snap ring for attachment to the right side gear to minimize endplay of the intermediate shaft. The chain sprocket is attached to the intermediate shaft by an expanding ring and the interaxle differential housing is supported by bearings, most preferably ball bearings. The intermediate shaft and the rear output shaft are supported by bearings, most preferably drawn cup needle roller bearings. The interior of the interaxle differential housing includes four (4) substantially flat thrust surfaces for support of the left side gear, a first pinion mate gear, the right side gear and second pinion mate gear. These four (4) substantially flat thrust surfaces allow the interaxle differential housing to be fabricated using a broaching manufacturing process to reduce fabrication cost. The first pinion mate gear and the second pinion mate gear are retained in the interaxle differential housing by stub shafts which are threaded into the interaxle differential housing wall. The stub shaft design includes a shoulder to provide controlled perpendicularity and torque retention and a recessed socket head to facilitate installation. A housing endcap is utilized for sealing and supporting the interaxle differential housing bearing and the input shaft and also to facilitate attachment of the all-wheel-drive motor vehicle transfer case with bevel gear differential to the motor vehicle transmission.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.